The present invention relates to an auxiliary device for a sewing machine for indicating the attachment of an interchangeable presser foot not corresponding to a determined machine set up for a sewing operation. The presser feet of a sewing machine are generally interchangeably attached to a shaft or directly to the presser bar of the machine and are accessories configured and used for performing determined sewing operations. The number of the presser feet associated to a sewing machine varies in accordance with the type and the equipment of the machine and it is often really difficult to distinguish the different presser feet from each other. For this reason, various precautionary indicators such as ciphers, symbols, colour codes and the like have been utilized in order to facilitate the distinction between them. However, should the user nevertheless attach a wrong presser foot to the machine, no precautionary measures are taken in order to call her attention to such an error.
The object of the present invention is to provide means which indicates and/or prevents the insertion of a wrong presser foot or prevents the starting of the machine when damages (breaking of the needle, injury of the presser foot) are likely to occur if a wrong presser foot is inserted.